Dyeing of films possessing low water imbibition



Dec. 31, 1946. R. c. GREENLEES DYEING OF FILMS POSSESSING LOW WATER IMBIBITION Filed 001;. 14, 1944 kWh fizveni-or RAYMOND CRAWFORD GREEN LEES . 3y his ailarney;

Patented Dec. 31, 1946 Y UNITED STATES PATENT OFFICE DYEING OF FILMS POSSESSINGL'OW WATER IMBIBITION Raymond Crawford Greenlees, Coventry, England, assignor to Courtaulds Limited, London, England, a company of Great Britain Application October 14, 1944, Serial No. 558,729 In Great Britain December 13, 1943 3 Claims.

This invention relates to the dyeing of fihns pzsssessing low water i'mbibition and is particulrly' concerned with the dyeing of such films in the dyebath, the fabric being run forwards and backwards from one roller to the other until the dyeing has proceeded to the desired extent. It is a characteristic of jig dyeing that as part of the dye liquor is taken up by the fabric during its passage through the dyebath, most of the dyeing takes place, not in the dyebath but whilst the fabric is Wound up on the rollers, When jig dyeing is applied to films of a thermoplastic material such as cellulose acetate, the Water imbibition of the film is so low that little or no liquor is taken up with the result that the dyeing operation is very time consuming,

I have found that the dyeing of films possessing low water imbibition, such as cellulose acetate films, on a jig or like machine is considerably expedited by associating the said film throughout its length with a fabric capable of taking up the dye liquor. The film is preferably associated with two fabrics. one on each side of the film. Generally speaking, films of thermoplastic material possess a low water imbibition.

According to a preferred embodiment of the invention, a film of cellulose acetate is placed between two lengths of a fabric, for example of cotton, and the whole is then wound on to one of the rollers fixed above the dyebath. The film and the fabrics are passed through the dyebath and wound up on th second roller and the pasdyeing of films of other organic derivatives of cellulose such as for example, cellulose propionate, cellulose butyrate, cellulose acetate-butyrate, cellulose acetate-propionate, ethyl cellulose acetate, ethyl cellulose and benzyl cellulose, or of other thermoplastic materials such as polymerised Vinyl acetate, polyvinyl chloracetate and polymerised alkyl substituted acrylic esters such as polymerised methyl methacrylate. The process of this invention is applicable to films which in addition to any one or more of the above materials also contain plasticising or softening agents of the usual type such as dimethyl phthalate, diethyl phthalate, dimethoxy'ethyl phthalate, dibutyl vphthalate, methyl and ethyl phthalylethyl g-lycollates, dimethyl, tartrate, diethyl tartrate, 'triphenyl phosphate, tricresyl phosphate, diacetin, tri'acetin and trichlorethyl phosphate..

1 Thefabric 'shouldpreferably be one which has very little or no aflinity for the dyestuif being employed in any particular instance. For example, when dyeing cellulose acetate film with a dispersed dyestuff such as Duranol Violet 2 R 300 (Imperial Chemical Industries Limited) a cotton or a viscose rayon fabric is suitable.

When dyeing cellulose acetate film according to this invention, it has been found that in order to prevent the film blushing permanently, it is desirable to dye at a temperature of about 65 to centigrade which is lower than usual for cellulose acetate fabric, and further the film should not be allowed to dry in the air at ordinary temperatures but should be dried immediately at to centigrade.

In the accompanying drawing Figure 1 shows the assembly of the films with two fabrics, one on each side,

Figure 2 is a section on the line II]I of Figure 1, and

Figure 3 is a diagrammatic end view of a jigdyeing machine suitable for use in carrying out the process of the invention.

The film l to be dyed is covered on both sides with the fabrics 2, 2. The assembled film and fabrics are then wound on the roller 3 to form the roll 4 comprising contacting layers of film I and fabric 2. To dye the film, the assembly 5 of film and fabric is led from the roller 3 into contact with the roller 6, under the guide roller 1 immersed in the dye liquor 8 in the bath 9, into contact with the roller Ill and Wound up on the roller ll. When the assembly 5 has passed com pletely through the bath 9 and is wound up on the roller II, it is passed through the bath in the opposite direction and is rewound on roller 3, the assembly being run backwards and forwards from roller 3 to roller II and back again until dyeing has proceeded to the desired extent.

This invention is illustrated by the following examples, the parts and percentages being by weight.

Example 1 A film 0.01 inch thick and 24 inches wide prepared from a composition containing 100 parts of cellulose acetate (57 per cent acetyl content calculated as acetic acid) 20 parts of dimethyl phthalate and 9 parts of triphenyl phosphate is placed between two lengths of cotton fabric and wound onto a roller, such as the roller 3 shown in the drawing. The whole is then jig-dyed in the manner described, at 65 centigrade with the usual ratio of weight of liquor to weight of film of 3:1 in a dyebath consisting of an aqueous dispersion containing 2 per cent of Duranol Violet 2 R 300, 0.2 per cent of Turkey red oil as dispersing agent, and 1 per cent of sodium hexametaphosphate. After dyeing, the film is immediately dried at 100 centigrade and will be found to possess a much deeper shade than a similar cellulose acetate film treated under identical conditions, but with the omission of the two sheets of cotton fabric.

Example 2 A length of cellulose acetate film of the same composition and dimensions as in Example 1 is placed between two lengths of a cotton fabric and then wound onto a roller and dyed on a jig dyeing machine in the manner described, for one hour at 65 centigrade with the same liquor to film ratio of 3:1 in a dyebath consisting of an aqueous dispersion containing 1.66 per cent of Dispersol Fast Yellow A 300 (Imperial Chemical Industries Limited), 0.83 per cent of Duranol Red X 3B 300 (Imperial Chemical Industries Limited), 0.2 per cent of Turkey red oil and 1 per cent sodium hexametaphosphate. The film is immediately dried at 100 centigrade and is found to be dyed to an amber shade.

In general the above-mentioned liquor to film but in cases where the cotton fabric is of such a nature as to absorb all the dye liquor in the dye-bath, it will be necessary to use a greater proportion of dye liquor in order to maintain a surplus supply thereof in the dyebath.

What I claim is:

1. A process of dyeing a film possessing low Water imbibition comprising covering a side of the film with afabric so that the fabric and film are in face to face contact throughout the length of the film, and then dyeing the film by passing the film and fabric through a bath of a selected dye color, and winding the film and fabric into a roll comprising contacting layers of film and fabric, whereby the fabric acts as a reservoir of a r dy liquor for the film and the film absorbs the dye from the dye liquor by virtue of its greater affinity for the dye.

2. A process as claimed in claim 1 wherein the film is associated with two fabrics, one on each side.

3. A process as claimed in claim 1 wherein the film is cellulose acetate.

RAYMOND CRAWFORD GREENLEES.

Certificate of Correction Patent No. 2,413,559.

RAYMOND CRAWFORD GREENLEES It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Column 4, line 21, claim 1, for the word color read liquor; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 4th day of March, A. D. 1947.

December 31, 1946.

LESLIE FRAZER,

First Assistant Commissioner of Patents. 

